Bone Plates and Associated Screws

ABSTRACT

A bone plate includes a bone-contacting surface, an upper surface opposite the bone-contacting surface, and a hole having a circumference and extending from the upper surface to the bone-contacting surface. The hole includes a first portion having a plurality of substantially parallel lips, each lip extends around the circumference of the hole and defines a diameter of the hole. The diameters of the hole, as defined by the lips, decrease in a direction from the upper surface to a center of the hole and increase in a direction from the center of the hole toward the bone-contacting surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.16/289,826, filed on Mar. 1, 2019, which claims the benefit of thefiling date of U.S. Provisional Patent Application No. 62/637,695 filedon Mar. 2, 2018, the disclosure of which is hereby incorporated hereinby reference.

BACKGROUND OF THE INVENTION

The present disclosure relates to a bone plating system and methods ofuse thereof for the fixation of fractures of the bone, particularly inlong bones, such as the femur, tibia, humerus and radius. Morespecifically, the present disclosure includes a bone plate systemincluding a plate with screw holes adapted to receive both locking andnon-locking screws and permit placement of those screws at variousangles.

When a bone is damaged or fractured, bone plates are commonly attachedto the outside surface of the damaged bone to stabilize the area andpromote healing of the bone. Generally, the plates have a bonecontacting side and a side facing away from the bone with a plurality ofholes extending through the two surfaces. The holes are typicallythreaded for use with locking screws or non-threaded for use withnon-locking, compression screws. Depending upon certain factors, such asbone quality and type, it may be more beneficial to utilize one type ofscrew over the other. Of course, the placement of dedicated locking andnon-locking holes in the plate limits where such screws can be utilized.Moreover, certain types of holes, especially threaded holes, facilitateplacement of a screw along only the axis of the hole.

There exists a need for holes that can receive both locking andcompression screws in placed at various angles with respect to the axisof the hole to provide surgeons with additional options for securing thebone plate to the bone and thereby fixing the fracture.

BRIEF SUMMARY OF THE INVENTION

The present disclosure generally relates to bone plating systems forreceiving locking screws in polyaxial orientations.

According to one aspect of the disclosure, a bone plate includes abone-contacting surface, an upper surface opposite the bone-contactingsurface, and a hole having a circumference and extending from the uppersurface to the bone-contacting surface. The hole includes a firstportion having a plurality of substantially parallel lips, each lipextends around the circumference of the hole and defines a diameter ofthe hole. The diameters of the hole, as defined by the lips, decrease ina direction from the upper surface to a center of the hole and increasein a direction from the center of the hole toward the bone-contactingsurface.

Other embodiments according to the first aspect may include each lipextending along a plane that is substantially perpendicular to a centralaxis of the hole. The hole may have a second portion that extends fromthe upper surface to the first portion, and a third portion that extendsfrom the bone-contacting surface to the first portion, the second andthird portions having substantially frusto-conically shapedcross-sections. The second and third portions may be devoid of lips. Thediameter of the hole may be smallest at about the center of the hole.Each lip may have a rounded cross-section.

According to another aspect of the present disclosure, a bone platingsystem includes a bone plate that has a hole that has a circumferenceand extends from an upper surface to a bone-contacting surface of thebone plate. The hole includes a first portion that has a series ofconcentric lips. Each lip extends around the circumference of the holeand defines a diameter of the hole, the diameters of the hole as definedby the lips decrease in a direction from the upper surface to a centerof the hole and increase in a direction from the center of the holetoward the bone-contacting surface. The bone plating system includes alocking screw receivable within the hole of the plate in polyaxialorientations. The screw has a threaded head and a frusto-conicalprofile. The threads of the head are configured to engage the lips ofthe hole to lock the screw to the plate.

Other embodiments of this aspect may include the plate being formed of afirst material and the screw being formed of a second material harderthan the first material. The lips of the hole may be elasticallydeformable by the threads of the screw to secure the screw to the plate.The head of the screw may have a double-lead thread. The bone platingsystem may include a compression screw receivable within the hole. Thelocking screw may be moveable in a 30 degree cone around a central axisof the hole. The bone plate may have a second portion extending from theupper surface to the first portion, and the compression screw may have ahead sized and shaped to rest in the second portion of the hole withoutextending into the first portion of the hole. Adjacent threads of thehead define a pitch, and adjacent lips of the hole define a pitch, thepitch of the threads may be substantially the same as the pitch of thelips.

In another aspect of the disclosure, a bone plating system includes abone plate that has a hole having a lip for engaging an outer surface ofan insert. The bone plate is formed of a first material. The bone plateincludes an insert that defines an opening for receiving a locking screwand has an outer surface for engagement with the lip of the hole. Theinsert is formed of a second material that is harder than the firstmaterial. The bone plating system includes a locking screw receivablewithin the insert.

In other embodiments of this aspect, the outer surface of the insert mayhave threads to engage the lip. The insert may have an inner surfacehaving threads, and the locking screw has a head having threadsconfigured to engage the threads of the inner surface of the insert tosecure the head to the insert. The threads of the inner surface of theinsert may be single lead and the threads of the outer surface of theinsert may be double lead. With the locking screw positioned within theopening of the insert, the locking screw and the insert may have coaxialcentral axes. The locking screw and insert may be configured to bearranged in polyaxial orientations with respect to a central axis of thehole. In such an arrangement, the central axes of the locking screw andthe insert may be positioned at a non-zero angle with respect to thecentral axis of the hole. The insert may be removeable from the hole ofthe plate.

In another aspect of the disclosure, a method of securing a bonefracture includes the steps of placing a bone-contacting surface of abone plate on bone, inserting a locking screw through a hole of theplate so that a shaft of the screw extends into bone and a head of thescrew is positioned within the hole, rotating the locking screw suchthat threads of the head engage a plurality of substantially parallellips positioned around a circumference of the hole to lock the screw tothe hole. Each lip extends around the circumference of the hole anddefines a diameter of the hole. The diameters of the hole as defined bythe lips decrease in a direction from the upper surface to a center ofthe hole and increase in a direction from the center of the hole towardthe bone-contacting surface.

According to other embodiments of this aspect, the head of the lockingscrew may have a frusto-conical shape. The bone fracture may be aperi-prosthetic fracture. The step of inserting may include insertingthe screw at an angle within a 30 degree cone with respect to a centralaxis of the hole. The plate may be formed of a first material and thescrew may be formed of a second material harder than the first materialand during the rotating step the lips of the hole deform. The method mayinclude the step of inserting a second locking screw into a second hole,the second hole being substantially identical to the first hole, androtating the second locking screw such that threads of the head engage aseries of concentric lips positioned around a circumference of thesecond hole to lock the second locking screw to the second hole. Thefirst screw may be locked at a first angle with respect to an axis ofthe first hole, and the second screw may be locked at a second anglewith respect to an axis of the second hole, the first and second anglesbeing different.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a top view of an illustrative bone plate according to anembodiment of the present disclosure;

FIG. 2 shows a perspective side view of the bone plate of FIG. 1;

FIG. 3 shows a cross-sectional view of a hole of the bone plate of FIG.1 according to an embodiment of the present disclosure;

FIG. 4 shows a cross-sectional view of the hole of FIG. 3 and a lockingscrew according to an embodiment of the present disclosure;

FIG. 5 is a cross-sectional side view of the system of FIG. 4, with thescrew inserted at different angles;

FIGS. 6 and 7 are cross-sectional views of a bone screw hole and lockingscrew according to another embodiment of the present disclosure;

FIG. 8 is an exploded perspective top view of a bone plating systemaccording to another embodiment of the present disclosure, with a focuson a hole and screw;

FIG. 9 is a cross-sectional view of the hole of the system of FIG. 8;

FIG. 10 is a cross-sectional view of the system of FIG. 8, with thescrew inserted within the hole;

FIG. 11 are perspective top and bottom views, respectively, of a nut ofthe system of FIG. 8;

FIG. 12 is a side view of the locking screw of the system of FIG. 8;

FIG. 13 is an exploded perspective top view of a bone plating systemaccording to another embodiment of the present disclosure, with a focuson a hole and screw;

FIG. 14 is a cross-sectional view of the system of FIG. 13, with thescrew inserted within the hole;

FIG. 15 is an enlarged cross-sectional view of the plate and hole andperspective views of the washer, cap and screw of the system of FIG. 13;

FIG. 16 shows a perspective side view of a locking key and washer of thesystem of FIG. 13;

FIG. 17 is a cross-sectional view of the hole and perspective bottomviews of the locking key, washer, and cap of the system of FIG. 13;

FIG. 18 is an exploded perspective top view of a bone plating systemaccording to another embodiment of the present disclosure, with a focuson a hole and screw;

FIG. 19 shows an exploded cross-sectional view of the system of FIG. 18;

FIG. 20 is a cross-sectional view of the system of FIG. 18;

FIG. 21 is a perspective side view of the washer, cap, and proximalportion of the screw head of the system of FIG. 18;

FIG. 22 is an exploded perspective top view of a bone plating systemaccording to another embodiment of the present disclosure, with a focuson a hole and screw;

FIG. 23 is a cross-sectional view of the plate hole of the system ofFIG. 22;

FIG. 24 is a cross-sectional view of the system of FIG. 22;

FIG. 25 is a perspective top view of the cap of the system of the FIG.22;

FIG. 26 is a perspective top view of the floating nut of the system ofFIG. 22;

FIG. 27 is a variant of the floating nut of FIG. 26;

FIG. 28 is a cross-sectional top view of a bone plating system accordingto another embodiment of the present disclosure, with a focus on a holeand screw;

FIG. 29 is a cross-sectional view of the hole and insert of the systemof FIG. 28;

FIG. 30 is a perspective top view of the hole in the plate of the systemof FIG. 28;

FIG. 31 is a perspective top view of the insert of the system of FIG.28;

FIG. 32 is a cross-sectional side view of a bone plating systemaccording to another embodiment of the present disclosure;

FIG. 33 is a top view of the screw of the system of FIG. 32;

FIG. 34 is a cross-sectional side view of a bone plating systemaccording to another embodiment of the present disclosure;

FIG. 35 is a perspective top view of the hole of the plate of the systemof FIG. 34;

FIG. 36 is a cross-sectional side view of a bone plating systemaccording to another embodiment of the present disclosure;

FIG. 37 is a perspective top view of the hole of the plate of the systemof FIG. 36;

FIG. 38 is a perspective side view of the locking screw of the system ofFIG. 36;

FIG. 39 is a cross-sectional side view of a bone plating systemaccording to another embodiment of the present disclosure;

FIG. 40 is a perspective top view of the hole of the plate of the systemof FIG. 39;

FIG. 41 is a perspective side view of the locking screw of the system ofFIG. 39;

FIG. 42 is a perspective side view of a variation of a locking screw ofthe system of FIG. 39;

FIG. 43 is a perspective bottom view of the screw head of the lockingscrew of FIG. 42;

FIG. 44 is a cross-sectional view of a bone plating system according toanother embodiment of the present disclosure;

FIG. 45 is a perspective top view of the hole of the plate of the systemof FIG. 44;

FIG. 46 is a perspective side view of the washer of the system of FIG.46;

FIG. 47 is a perspective side view of the locking screw of the system ofFIG. 44;

FIG. 48 is a cross-sectional side view of a bone plating systemaccording to another embodiment of the present disclosure;

FIG. 49 is a perspective top view of the hole of the plate of the systemof FIG. 48;

FIG. 50 is a perspective side view of the washer of the system of FIG.48;

FIG. 51 is a perspective side view of the locking screw of the system ofFIG. 48;

FIG. 52 is a cross-sectional side view of a bone plating systemaccording to another embodiment of the present disclosure;

FIG. 53 is a cross-sectional side view of a bone plating systemaccording to another embodiment of the present disclosure;

FIGS. 54A and 54B are perspective top and side views of the lockingscrew of the system of FIG. 53;

FIG. 55 is a cross-sectional side view of a bone plating systemaccording to another embodiment of the present disclosure; and

FIG. 56 is a perspective top view of the hole of the plate of the systemof FIG. 55;

FIG. 57 shows a cross-sectional view of a hole according to anotherembodiment of the present disclosure;

FIG. 58 is a top view of the hole of FIG. 57;

FIG. 59 is a cross-sectional view of the hole of FIG. 57 in conjunctionwith a locking bone screw;

FIG. 60 is a side perspective view of a non-locking screw for use withthe hole of FIG. 57;

FIG. 61 is a cross-sectional view of an alternative embodiment of thehole of FIG. 57;

FIG. 62 is another alternative embodiment of the hole of FIG. 57;

FIG. 63 is a top view of the hole of FIG. 62;

FIG. 64 is a cross-sectional view of yet another alternative embodimentof the hole of FIG. 57; and

FIG. 65 is a top view of the hole of FIG. 64.

DETAILED DESCRIPTION

As used herein unless stated otherwise, the term “anterior” means towardthe front part of the body, and the term “posterior” means toward theback part of the body. When referring to specific directions in thefollowing discussion of a certain device, the terms “proximal” and“distal” are to be understood in regard to the device's orientation andposition during exemplary application to human body. Thus, the term“proximal” means closer to the operator or in a direction toward theoperator, and the term “distal” means more distant from the operator orin a direction away from the operator. In addition, the terms “about,”“generally,” and “substantially” are intended to mean that deviationsfrom absolute are included within the scope of the term so modified.

Additionally, certain of the embodiments include similar features, forwhich similar reference numerals are utilized, albeit within a different100-series of numbers. For instance, FIGS. 1-5 illustrate a polyaxialscrew system 20, while FIGS. 6 and 7 illustrate a system 120.

Referring to FIGS. 1-5, an embodiment of a polyaxial screw system 20 forthe fixation of bone fractures according to the present disclosure isshown. System 20 includes illustrative bone plate 30 defining plateholes 40 adapted to receive locking and/or non-locking screws.Generally, embodiments of the present disclosure include bone platesthat may be similar to plate 30, although each embodiment includes adifferent feature that enables polyaxial locking of screws within holes40, as will be described in further detail below. Further, each of thebone plates of the present disclosure may receive locking screws,compression screws, or a combination of both in the plurality ofpolyaxial holes 40. Although one type and/or shape of plate 30 is shownherein, and such plate may indeed be novel and unobvious in view of theprior art, it is to be understood that plates according to the presentinvention can be designed for use on various bones and thusly can be anyconfiguration necessary for such use. Indeed, certain plate sizes andshapes are well known for certain applications and the different holeconfigurations noted below can be utilized therewith.

In the illustrated embodiment, plate 30 includes bone-contacting surface32 and upper surface 34 opposite the bone-contacting surface. In animplanted configuration, bone-contacting surface 32 is positioned on thebone and upper surface 34 is substantially opposite to thebone-contacting surface. Generally, throughout the various embodimentsof the present disclosure, the term “inferior” means toward thebone-contacting surface and the term “superior” means toward the uppersurface.

Plate 30 defines a length extending from first end 36 to second end 38.In the embodiment shown, plate 30 has a substantially constant platethickness. First end 36 is anatomically formed to conform to thetrochanter region of the femur. In particular, in an implanted state,first end 36 conforms to the convex surface of the femur in the regionof the greater trochanter. Second end 38 is anatomically formed toconform to the condyle region, in particular the convex surface of thefemur in the region of the medial condyle. As such, plate 30 providesconformity both in the trochanter region and in the condyle region ofthe femur, without requiring intense contouring when fixing the plate tothe femur. In another embodiment, the plate thickness may vary along thelength of the plate. Plate 30 may be formed from a single piece of rigidmaterial, such as stainless steel, titanium and its alloys.

As shown in FIGS. 1 and 2, plate 30 may include at least one oblong hole39 extending from bone-contacting surface 32 to upper surface 34 forreceiving a non-locking screw. Oblong hole 39 may have a lengthextending in the same direction as the length of plate 30 and preferablyacts in conjunction with the non-locking screw to compress a fracture,such as a peri-prosthetic fracture. Plate 30 also includes a pluralityof holes 40 extending from bone-contacting surface 32 to upper surface34. Holes 40 are circular, although in other embodiments the holes mayhave a different shape. Holes 40 are configured to accept locking andnon-locking screws and at varying angles with respect to an axis formedthrough the hole, shown in FIG. 5. In other words, the holes include apolyaxial locking feature. Generally, embodiments of the presentdisclosure include bone plates that may be similar to plate 30, althougheach embodiment includes a different feature that enables polyaxiallocking of screws within holes 40, as will be described in furtherdetail below. Although holes 40 are described herein with connection toplate 30, the holes may be employed on a bone plate having any shape,and the bone plate shown in FIGS. 1-2 is not meant to be limiting.

FIGS. 3 and 4 show enlarged cross-sectional views of one of the holes 40of plate 30. Hole 40 extends along a central hole axis that issubstantially perpendicular to bone-contacting and upper surfaces 32,34, respectively. Hole 40 includes central portion 52 formed of aplurality of non-threaded lips 44 extending around the circumference ofthe hole, such that each lip completes a revolution around the hole.Each lip 44 defines a specific diameter of the hole. For example, asuperior-most lip defines a first diameter of the hole, and the lipadjacent the superior-most lip defines a second diameter of the holedifferent than the first diameter. As shown, these diameters decreasetowards the middle of the hole and increase again towards the bottom ofthe hole so as to create a substantially curved cross-section in theinterior of the hole. Lips 44 are substantially parallel and concentricto one another, and each lip is substantially perpendicular to thecentral axis of the hole. In the illustrated embodiment, each lip 44 hasa round cross-section, although in alternative embodiments, thecross-section may be trapezoidal, triangular, or any other shape.

As shown in FIG. 3, each lip includes a crest 46 extending between twotroughs 48. Central portion 52 has a substantially spherical profile,although, certain of the lips 44 may be configured such that the profilebetween those respective lips is tapered rather than rounded. The pitch,i.e., the distance between adjacent lips such as from crest to crest,may be substantially the same for the plurality of the lips, and atleast two pairs of adjacent lips have the same pitch.

Hole 40 includes upper portion 50 extending from upper surface 34 to asuperior-most lip 44 and lower portion 54 extending from bone-contactingsurface 32 to an inferior-most lip 44. Hole 40 has a relatively largerdiameter at upper portion 50 than at lower portion 54. Upper and lowerportions 50, 54 are conically tapered and have smooth, flat surfaces andform countersinks. Upper portion 50 and lower portion 54 may taper atsubstantially the same or different angles or may not taper at all(i.e., extend perpendicular to the surfaces).

As shown in FIGS. 4 and 5, locking screw 60 includes head 62 and shaft68. Head 62 has a hexagonal socket 64 for mating engagement with adriving tool (not shown). Although socket 64 is shown has having ahexagonal shape, the socket can be any shape suitable for transmittingtorque from a correspondingly shaped driver tool. Head 62 has asubstantially frusto-conical shape and is threaded. The pitch, i.e. thedistance between adjacent threads, is substantially equally to the pitchof the lips 44 of the hole 40. Head 62 may include a double entrythread, but in other embodiments, the head may include a single entrythread. Shaft 68 extends along a longitudinal axis of the screw 60 andis threaded along its length. Screw 60 may be formed from a materialthat is harder than the material that plate 30 is formed from. Forexample, screw 60 may be formed from cobalt chromium, while plate 30 maybe formed of titanium and its alloys.

In use, bone-contacting surface 32 is positioned on the damaged bone.Locking screw 60 is inserted into hole 40 with head 62 positioned withinand surrounded by hole 40 and shaft 68 extending through bone-contactingsurface 32 and into the bone. Screw 60 may be inserted into the holewithin a cone of 30 degrees with respect to an axis of the hole. Forinstance, FIG. 4 shows screw 60 inserted within the hole at about 15degrees relative to the central axis of the hole, and FIG. 5 shows thescrew inserted positioned at about 0 degrees relative to the centralaxis of the hole. With screw 60 within hole 40, the screw may betorqued. Due to the conical shape of head 62, the head applies radialforces to the bone plate 30 so that the threads of the head engage lips44 of the hole, which results in a form fit. Because screw 60 is formedof a harder material than bone plate 30, the bone plate and lips 44 mayelastically deform, locking the screw into the hole of the plate at thedesired angle. Thus, plate 30 may have a plurality of holes 40, and eachscrew 60 may be placed at a same or different angle with respect to theaxes of the bone holes.

Alternatively, a compression screw (not shown) may be inserted into hole40 and secured to the bone. The head of such screw may rest within upperportion 50, without extending into central portion 52. As such, platesystem 20 can accommodate locking screws 60, in the manner describedabove, as well as compression screws in holes 40. The plurality of theholes 40 of plate 30 may include all locking screws 60, or allcompression screws, or a combination of both.

In another embodiment of the present disclosure, system 120 is similarin most respects with system 20. Similar reference numerals are utilizedfor similar features but within the 100 series of numbers, the similarfeatures of which will not be described again. Significantly, plate 130includes holes 140 which employ a different locking feature than holes40 of plate 30.

As shown in FIGS. 6 and 7, system 120 includes bone plate 130 withpolyaxial locking holes 140. Each hole 140 includes central portion 152with a single lip 144 projecting inward toward a center line of the holeand extending around the circumference of the hole. Lip 144 forms aseating surface that allows for engagement and locking with lockinginsert 170, described in further detail below. Lip 144 includes uppertapered surface 146 and lower tapered surface 148 with central surface145 extending between them. Upper and lower tapered surfaces 146, 148may taper at substantially same or at different angles from one another.Central surface 145 extends in a plane substantially parallel to thecentral axis of hole 140 and substantially perpendicular to uppersurface 134. Lip 144 may be integral with hole 140 of plate 130 so as tobe manufactured as a monolithic, single piece.

Hole 140 also includes upper portion 150 extending from upper surface134 to central portion 152 and lower portion 154 extending frombone-contacting portion 132 to central portion 152. Hole 140 has arelatively larger maximum diameter at upper portion 150 than at lowerportion 154. Upper and lower portions 150, 154 are conically tapered andhave smooth, flat surfaces and form countersinks. Upper portion 150 andlower portion 154 may taper at substantially the same or differentangles or not taper at all.

Locking screw 160 includes head 162 and shaft 168. Head 162 has ahexagonal socket 164 for mating engagement with a driving tool (notshown). Although socket 164 is shown has having a hexagonal shape, thesocket can be any shape suitable for transmitting torque from acorrespondingly shaped driver tool. Head 162 is threaded and includes amale thread which may be a single entry or double entry thread. Head 162may be frusto-conically shaped. Shaft 168 extends along a longitudinalaxis of the screw 160 and is threaded along its length.

Insert 170 has a generally frusto-conical shape and includes innersurface 172 and outer surface 174, opposite the inner surface. The shapeof insert 170 may be designed to match the frusto-conical shape of screwhead 162, although the diameter of the insert is at least slightlylarger than that of the screw head so that the insert can fit around thescrew head. Inner surface 172 includes female threads that match andmate with the male threads of screw head 162. Outer surface 174 includesa double entry, sharp male thread to grip lip 144 to engage the lip andallow poly axial locking of screw 160.

Insert 170 may be formed of a material that is harder than plate 130.For example, insert 170 may be formed of cobalt-chromium (CoCr), andplate 130 may be formed of titanium and its alloys, e.g. Ti6Al4V ELI.Screw 160 may be formed of titanium and its alloys, e.g. AxSOS 3Titanium, although the hardness of the screw is not relevant relative tothe hardness of the plate.

Prior to insertion in a patient, shaft 168 of screw 160 may be placedthrough insert 170 such that head 162 of the screw is surrounded by theinsert. Head 162 and inner surface 172 of insert 170 have correspondingmating threads, so that the screw can be rotated and secured to theinsert. In this manner, screw 160 extends in a direction along a centralaxis of insert 170, so that the screw and insert are co-axial. Thisscrew-insert configuration may then be inserted into hole 140 of plate130 during surgery. Alternatively, the insert may be positioned withinthe hole first, and then the screw inserted through both the insert andthe hole.

During surgery, with bone-contacting surface 132 of plate 130 positionedadjacent the bone, the screw-insert configuration may be inserted intohole 140 such that shaft 168 of the screw is driven into the bone. Thescrew-insert configuration may be inserted in multiple angles as system120 allows polyaxial orientations of the screw-insert configuration. Asscrew 160 is torqued, the threads on outer surface 174 of insert 170engage lip 144 of hole 140. Because the insert is formed of a hardermaterial than the hole, the lip may elastically deform to secure thescrew-insert configuration at the desired angle. The screw-insertconfiguration is formed of separate, independent elements, although theelements may be assembled in the operating room to reduce or avoid therisk of contamination.

Like system 20, plate system 120 can accommodate locking screws 160, inthe manner described above, as well as compression screws (not shown) inholes 140. The plurality of the holes 140 of plate 130 may include alllocking screws 160, or all compression screws, or a combination of both.

In another embodiment, FIGS. 8-12 show bone plating system 220 of thepresent disclosure. That system includes a plate 230 that employs aplurality of polyaxial holes 240 that extend from upper surface 234 tobone-contacting surface 232. Hole 240 includes upper portion 250 thatextends from upper surface 234 to rim 245, which extends fartherradially inward toward the center of the hole than the upper portion.Rim 245 continues into central portion 252, such that the rim forms anedge between upper portion 250 and central portion 252. Central portion252 of hole 240 includes a plurality of spaced-apart, rounded concavecavities 246. In the illustrated embodiment, the cavities arespaced-apart at about 90 degrees from each other.

As shown in FIGS. 8 and 10, hole 240 is designed to accept a floatingnut 271 and cap 280. Nut 271 is mounted in hole 240 and has a concave“bowl-shape” that defines a hollow interior region into which bone screw260 can be inserted. With specific reference to FIG. 11, nut 271includes inner surface 273 and outer surface 274, opposite the innersurface. Due to the “bowl-shape” of nut 271, it tapers gradually inwardfrom first end 275 to second end 277. Inner surface 273 includesparallel lips at second end 277 to mate with the male threads of screw260. Protrusions 276 extend radially outward of outer surface 274 andare spaced-apart from one another on the outer surface. Protrusions 276are positioned relative to each other in the same manner as cavities 246of hole 240, and accordingly, in the illustrated embodiment, theprotrusions are spaced apart about 90 degrees from one another.Protrusions 276 are designed to fit within and engage cavities 246 ofhole 240. Engagement of the protrusions 276 with cavities 246 of hole240 prevent nut 271 from rotating around the hole, although the nut isfreely movable in a conical motion.

System 220 further includes cap 280 welded or otherwise securedly fixedwithin hole 240 and positioned superior to nut 271, that is the cap iscloser to upper surface 234 than nut 271 is to the upper surface. Withreference to FIG. 10, cap 280 includes support 281 and annular collar283 that forms a shoulder of the cap and extends radially outward of thesupport. Cap 280 defines a concave interior opening into which screw 240can be inserted. Support 281 of cap 280 has an outer diameter that isless than the inner diameter of nut 271 at first end 275 of the nut suchthat the support may be positioned within the nut with collar 283forming a shoulder that abuts first end 275 of the nut, as shown in FIG.10. Collar 283 sits within upper portion 250 of hole 240 and is securedin place by rim 245 of the hole.

Referring to FIG. 12, system 220 further includes screw 260 with head262 and shaft 268 extending along a longitudinal axis of the screw. Head262 is substantially spherically shaped, and as shown in the illustratedembodiment, the screw head is not threaded. Shaft 268 is threaded andincludes top portion 268 a with double lead threads and bottom portion268 b with single lead threads. The threads on top portion 268 a aremale threads that engage the parallel lips of nut 271 to secure thescrew to the nut.

In use, screw 260 is inserted through hole 240, nut 271, and cap 280.Prior to locking the screw, nut 271 is “floating.” This means that thenut has a conical range of motion within the hole and can move along thespherical surface of central portion 252, which occurs prior to thescrew being torqued into a final position. The “floating” arrangement ofthe nut allows polyaxial orientations of the screw within the hole. Asscrew 260 is rotated, the male threads of top portion 268 a of the screwshaft engage the parallel lips of nut 271. Protrusions 271 of nut 271engage cavities 246 of the hole, to prevent the nut from rotating aroundthe hole. As the spherical head 262 of the screw contacts cap 280, nut271 is forced toward the cap causing friction between the nut and thecap to lock the screw to the plate.

In another embodiment, FIGS. 13-17 show bone plating system 320 of thepresent disclosure. System 320 includes bone plate 330 with a pluralityof holes 340 and screws 360, each with threaded conical head 362 andthreaded shaft 368. Each hole 340 includes floating washer 371 and cap380, which is welded or otherwise securedly fixed to the hole.

As shown in FIGS. 13-15, hole 340 includes an upper portion 342 thatincludes a stepped arrangement that defines different diameters of thehole. In the illustrated embodiment, there are two steps, a first stepincluding flat surface 345 a and a second step including flat surface345 b. Flat surfaces 345 a and 345 b extend around the circumference ofthe hole, with flat surface 345 b defining a smaller diameter of thehole than flat surface 345 a.

Hole 340 further includes lip 346 extending from the inferior-most stepto bone-contacting surface 332. Lip 346 includes upper and lower taperedsurfaces 348, 349, respectively, with central surface 350 extendingbetween them. Upper tapered surface 348 and lower tapered surface 349may taper at a substantially same or at different angles from oneanother. Central surface 350 extends in a plane substantially parallelto the central axis of hole 340 and substantially perpendicular to uppersurface 334 of bone plate 330.

System 320 includes washer 371 mounted in hole 340 that has a“disc-shape” and defines an interior opening extending from uppersurface 372 to lower surface 374. The distance between upper surface 372and lower surface 374 defining a width of the washer. Upper surface 372includes at least one ramp 373 such that the two sides of the uppersurface 372 adjacent a ramp 373 are not in a continuous plane, such thatthe width of the washer is not uniform around its circumference. Washer371 includes a plurality of spaced apart concave recesses 378 on innersurface 376. Washer 371 is designed to sit on lower surface 345 b of theinferior-most step of hole 340.

Cap 380 is welded into hole 340 superior to washer 371, i.e. closer toupper surface 334 of bone plate 330. Cap 380 has a “disc-shape” anddefines an interior opening. Cap 380 includes at least one ramp 383 onits lower surface 384 that corresponds to ramp 373 on the upper surface372 of washer 371. Cap 380 is welded to sit on lower surface 345 a of astep of hole 340.

In use, washer 371 is freely moveable along a horizontal plane butrotation of the washer is limited due to the ramps. With screw 360inserted in hole 340 and thus through cap 380 and washer 371, a firstportion of threaded screw head 362 engages washer 371 and a secondportion of the screw head engages lip 346. Because washer 371 can movehorizontally with respect to lip 346, the screw may be arranged atvariable angles with two locking planes, i.e. a first plane extending atthe point of contact of the screw head and the washer and a second planeextending at the point of contact of the screw head and the lip.

The washer may be locked at the desired angle by the rotation of screw360. As the screw is rotated, the washer also initially rotates.However, due to the ramps, as the washer rotates, the ramps act as awedge to lock the washer in position.

Alternatively, as shown in FIGS. 16-17, locking key 390 may be used insystem 320 to fix the washer in a desired position prior to insertion ofscrew 360. Locking key 390 has a substantially cylindrical shapedefining opening 392 extending along the longitudinal axis of the key.Locking key 390 includes projections 394 spaced apart around acircumference of the key and extending radially outward from an outersurface near end 398 of the key. Projections 394 are sized and shaped tobe received within recesses 378 of the washer 371.

In use, locking key 390 is inserted through hole 340, cap 380, andwasher 371. Locking key 390 may be inserted in polyaxial orientations,and as key 390 is rotated, projections 394 of locking key 390 engagerecesses 378 of washer 371. Rotation of washer 371 locks the washer inthe desired position, with key 390 at a desired angle within hole 340.After removal of key 390, screw 360 is inserted in hole 340 at the sameangle as key 390 had been positioned. Thus, use of locking key 390allows for polyaxial locking of screw 360.

In yet another embodiment, FIGS. 18-21 show bone plating system 420 ofthe present disclosure. System 420 is similar in most respects to system320, although the system results in a single locking plane, and anadditional guiding plane rather than two locking planes, as will bedescribed below. Similar reference numerals are used for similarfeatures, although in the 400 series.

System 420 includes a plurality of holes 440 similar to holes 340 exceptthat hole 440 includes a partial lip 446 formed of tapered surface 448and central surface 450 extending from bone-contacting surface 432 totapered surface 448.

Screw 460 includes conical head 462, shaft 468, and smooth roundedtransition portion 465 extending between the head and the shaft andhaving a substantially spherical profile. Head 462 and shaft 468 arethreaded, while transition portion 465 is not.

Hole 440 of plate 430 functions similarly to hole 340, except thatpartial lip 446 engages non-threaded transition portion 465 of the screwto provide support to the screw but does not lock the screw along theplane of contact with the partial lip. Thus, hole 440 provides for onelocking plane along washer 471, and an additional plane of support atpartial lip 446.

FIGS. 22-27 show yet another embodiment of a bone plating system of thepresent disclosure. System 520 includes bone plate 530 with a pluralityof holes 540 and screws 560 that are similar to screws 460 of boneplating system 420. In particular, screws 560 include threaded head 562,non-threaded transition portion 565, and shaft 568. Non-threaded portion565 may be convex, concave, or cylindrically shaped, although in theillustrated embodiment, it is convex.

As shown in FIG. 23, hole 540 includes first portion 550 extending fromupper surface 534 to second portion 554 that extends to third portion553 which terminates at bone-contacting surface 532. First portion 550has a conically inward tapering profile and second portion 554 has asubstantially spherical profile. Third portion 553 tapers outwardlytoward bone-contacting surface 532 or in another embodiment it may havea substantially straight profile.

As shown in FIGS. 22 and 24-27, system 520 includes “floating” nut 571moveable within the hole and cap 580 welded or otherwise securely fixedto plate hole 540. Both cap 580 and nut 571 have openings to receivescrew 560.

As best shown in FIGS. 24 and 25, cap 580 is annular with base portion582 having inner and outer base surface 582 a, 582 b, respectively andwall 584, including inner and outer wall surfaces 584 a and 584 b,respectively. Wall 584 terminates in flat surface 585, the wall“standing up” from base portion 582. As best shown in FIG. 24, outersurface 584 b of wall 584 is curved inwardly. Base 582 is sized andshaped such that outer surface 582 b of the base fits within thirdportion 554 of the hole.

Referring to FIG. 24, cap 580 is positioned within hole 540 such thatlower surface 581 extends substantially parallel to bone-contactingsurface 532. Base 582, and in particular outer surface 582 b of thebase, is positioned against the inner surface of hole 540. Thispositioning of the base against the inner surface of the hole creates anopening between the inner surface of the hole and wall 584 into which aportion of nut 571 can be received.

As shown in FIG. 24, nut 571 is sized and shaped to fit within theopening between the inner surface of the hole and wall 584 of the cap.Nut 571 has a substantially spherical shape that has at least one ramp575 on the outer surface 573 of the nut, shown in FIG. 25. In theillustrated embodiment, outer surface includes four ramps 575. In avariant of the embodiment, shown in FIG. 26, outer surface 573′ of nut571′ may include a series of teeth extending around a circumference ofthe outer surface. In this example, the teeth form concentric ridgesextending around the outer surface.

Nut 571 includes ledge 578 extending radially inwardly around innersurface 576 at upper end 572 of the nut. Ledge 578 is threaded to matewith the threads of screw head 562. Ledge 578 sits on flat surface 585of wall 584, and the nut is received within the space between wall 584and the inner surface of the hole. In this position, nut 571 can “float”or move poylaxially with respect to cap 580 and hole 540 in a directionalong the wall 584 of the cap, but the nut is limited in rotationalmovement by the ramps on its outer surface 573.

In use, screw 560 is positioned in hole 540 through nut 571 and cap 580such that non-threaded transition portion 565 of the screw contacts lip588 of the cap. Nut 571 is moveable along the spherical surface ofsecond portion 554 of the hole to allow for polyaxial orientations ofscrew 560 in hole 540. Screw 560 may be rotated, and the threads onscrew head 562 engage the threads on nut 571 to lock the screw to thenut. Rotation of screw 560 imparts a rotational force on nut 571. As nut571 is rotated, ramps 575 on outer surface 573 of the nut pinch againstthe inner surface of the hole to fix the nut in position.

Alternatively, nut 571 may be fixed to the plate at the desired angle byrotation of a tool (not shown). The screw may then be inserted into thehole and rotated to engage the threads of the nut to lock the screw tothe nut and the plate.

In yet another embodiment of the present disclosure, FIGS. 28-31 showbone plating system 620 including bone plate 630 with a plurality ofholes 640 and screws 660, each with threaded conical head 662 andthreaded shaft 668. Each hole 640 includes insert 670 received withinthe hole and allowing for polyaxial locking of screw 660.

Referring to FIG. 30, hole 640 includes a plurality of projections 644 aextending inwardly toward the center of the hole. In the illustratedembodiment, each projection extends in a direction along a central axisof the hole, and each projection is adjacent a substantially roundedtrough 644 b. Projections 644 a may be separated into two rows andspaced apart from one another along the central axis of the hole by“zig-zag” groove 645. Groove 645 extends around the circumference of thehole.

Referring to FIG. 31, insert 670 may be inserted within hole 640 toallow for polyaxial locking of screw 660. Insert 670 has a substantiallycylindrical shape and includes inner surface 672 and outer surface 674,opposite the inner surface defining an opening for receiving screw 660.Insert 670 does not form an enclosed annular shape, rather the insertincludes two open ends 671 that define an opening between the open endsforming a “C-shape.” Two pairs of two rounded tabs 675 project radiallyoutward of outer surface 674 spaced about 180 degrees from one another,the tabs sized and shaped to fit within troughs 644 b of hole 640.Recess 676 extends through inner surface 672 and terminates within thebody of the insert so as not to extend through outer surface 674. Innersurface 672 includes at least two columns of teeth 678. The columns ofteeth 678 have substantially spherical profile, best shown in FIG. 29.Insert 670 further includes curved passage 679 opposite open ends 671that extends into the body of the insert from inner surface 672 but doesnot extend through outer surface 674. Although not shown, outer surface674 of the insert may include serrations to engage the hole.

Insert 670 is rotatable 360 degrees within hole 640 prior to locking ofscrew 660, which allows for polyaxial orientations of the screw. Insert670 is secured to the hole by a retaining ring. In use, screw 660 isplaced within insert 670, and the screw is moveable along one plane.Screw 660 is rotated, and head 662 forms an interference fit with thecolumns of teeth of the insert. As the screw is advanced through hole640, open ends 671 of the insert move away from one another to open theinsert. As insert 670 opens tabs 675 engage troughs 644 b of the hole toprevent rotational movement of the insert.

FIGS. 32-33 show bone plating system 720 according to another embodimentof the present disclosure. System 720 includes bone plate 730 havingholes 740 and locking screws 760.

Referring to FIG. 32, hole 740 includes first portion 750 extending fromupper surface 734 of plate 730 to second portion 754. First portion 750has a concave shape and includes lip 748 extending around thecircumference of the inner surface of hole 740. Second portion 754extends from first portion 750 to bone-contacting surface 734 of thehole and defines a substantially flat edge. Hole 740 has a largerdiameter at upper surface 734 than at bone-contacting surface 732.

Screw 760 includes head 762, shaft 768, and neck 765 extendingtherebetween. Head 762 includes concave relief portions 763 around thehead to allow for easy locking and prevent collision of the head withthe hole. From the top view, shown in FIG. 33, head 762 has asubstantially oval shape. Neck 765 has a diameter that is smaller thanthe diameter of the head and of the shaft, as shown in FIG. 32.

In use, the oval shape of head 762 allows the head to snap into lip 748of hole 740. Head 762 has a roughened outer surface to prevent slippingof the screw head. With the head engaged with lip 748, the lip preventsthe screw from pulling out of the hole.

In yet another embodiment, FIGS. 34-35 show bone plating system 820 ofthe present disclosure. System 820 includes holes 840 extending throughplate 830 from upper surface 834 to bone-contacting surface 832. Holes840 are configured for polyaxial locking, as will be described below.

Hole 840 includes thin engagement section 844 extending inward from aninner surface of the hole toward the center of the hole. Engagementsection 844 extends at an angle toward upper surface 834 of the plate asshown in FIG. 36. In the illustrated embodiment, engagement section 844forms a convex, rounded surface. Engagement section 844 defines anannular opening with a relatively smaller diameter than the diameter ofhole 840 at upper surface 834 of the plate.

Screw 860 includes head 862 having a lower surface 863 that rests onengagement section 844 of the hole 840. Lower surface 863 forms aconcave surface to mate with the convex surface of the engagementsurface. Screw 860 may have a roughened outer surface on head 862 tocreate surface bonding between the hole and the screw. After screw 860is inserted in hole 840, the screw is rotated. Rotation of the screwcauses engagement section 844 to flex and bend, which creates anopposing force to secure the screw to the plate at variable angles.

FIGS. 36-38 show bone plating system 920 according to another embodimentof the present disclosure. System 920 is similar to system 820 andincludes plate 930 with holes 940 configured to receive locking screws960. Holes 940 include engagement section 944, similar in most respectsto engagement section 844 of hole 840. Engagement section 944 may besubstantially rounded to form a convex surface, as shown in FIGS. 36 and37.

Screw 960 is similar to screw 860, the similar features of while willnot be repeated. Screw head 962 includes at least teeth 964 projectingfrom lower surface 963 of the screw head in a direction toward a distalend of shaft 968. Teeth 964 may terminate in a sharp point, a knifeedge, or may be hooked. In other examples, teeth 964 are shaped in anymanner to form a sharp point or edge of the tooth. In the illustratedembodiment, there are two teeth 964 spaced about 180 degrees from eachother. Screw 960 is formed of a material that is harder than a materialthat plate 930 is formed of.

In use, screw 960 is inserted in hole 940, and torqued. As screw 960 istorqued, the sharp edges of teeth 964 of the head 962 dig intoengagement section 944 of hole 940 and lock the screw to the hole at thedesired angle.

In another embodiment of the present disclosure, FIGS. 39-43 show boneplating system 1020, similar to system 920. System 1020 includes boneplate 1030 with holes 1040 extending through the plate and adapted toreceive and lock screw 1060 in polyaxial orientations.

Hole 1040 includes engagement section 1044 similar in most respects toengagement section 944, except that engagement section 1044 includes aplurality of grooves 1046 extending into superior surface 1044 a of theengagement section around the circumference of engagement section 1044.Engagement section 1044 further includes a plurality of lips 1047adapted to engage a corresponding snap feature on screw 1060, furtherdescribed below. Each lip 1047 is positioned between two grooves 1046.

Referring to FIG. 41, screw 1060 includes head 1062 have a substantiallyflat side surface 1063 and a concave lower surface 1063. Lower surface1064 includes at least one snap feature to grip to grooves 1046 and lips1047 of the engagement section 1044 of the hole. The illustratedembodiment includes projection 1066 extending along a longitudinal axisfrom side surface 1063 in a direction toward a distal end of the shaft1068. Projection 1066 includes at least one groove 1067 extending in adirection transverse to its longitudinal axis. Groove 1067 mates withlips 1047 of the hole to secure the screw 1060 to the hole. In theillustrated embodiment, screw 1060 includes two snap features, namelytwo projections 1066 spaced 180 degrees apart from one another on head1062.

In use, screw 1060 is inserted within hole 1040 and torqued. As torqueis applied to the screw head 1062, projections 1066 deform to create asnapping effect with lips 1047 and grooves 1047 to lock the projectionand the screw to the hole while allowing the screw to be positioned atvariable angles.

FIGS. 42-43 show a variant of bone system 1020 having screw 1060′ thatdiffers from screw 1060. Screw 1060′ includes a plurality of grooves1067′ on concave lower surface 1063′ of the head 1062′. Grooves 1067′extend around the lower surface and may be helically wound around thehead; alternatively, the grooves extend in parallel, concentric planesaround the lower surface of the head. Grooves 1067′ mate with the lipsof the engagement section of the hole and snap onto the lips to lock thescrew head to the hole in polyaxial orientations. In both variants ofsystem 1020, grooves 1067 of the engagement section of the hole providehigher bending stiffness to the engagement stiffness.

In yet another embodiment of the present disclosure, FIGS. 44-47 showbone plating system 1120 having holes 1140 for receiving screws 1160 inpolyaxial orientations. Holes 1140 are threaded to mate with thethreading on screw head 1162. System 1120 includes washer 1170 which is“C-shaped” and includes external threads for locking the washer to thehole. Further, washer 1170 has a substantially concave inner surface. Asshown in FIG. 47, screw 1160 includes head 1162, shaft 1168, andtransition portion 1165 therebetween. Transition portion 1165 has aconvex shape.

In use, washer 1170 is positioned around transition portion 1165 andinserted into hole 1140. The external threads on washer 1170 mate withthe threads of hole 1140 to secure the washer to the plate. Due to theconvex shape of transition portion 1165 of screw 1160 and the concaveshape of the inner surface of washer 1170, the screw-washer interfaceacts as a ball-and-socket joint, and the screw can move polyaxially. Thescrew may have a rough surface finish to secure the screw to the washer.

FIGS. 48-51 show bone plating system 1220 that is similar in mostrespects to bone plating system 1120, the similar features of which willnot be described again. System 1220 includes plate 1230 with a pluralityof holes 1240. Each hole 1240 has a substantially concave shape andincludes a single lip 1244 positioned closer to bone-contacting surface1232 than upper surface 1234. Hole 1240 includes “C-shaped” washer 1270assembled to the hole and secured therein by snap fit. Washer 1270includes internal threads, as shown in FIG. 50. Screw 1260 includes head1262, shaft 1268, and transition portion 1265 therebetween. Transitionportion 1265 is convex, and includes external threads to mate with thethreads of washer 1270.

In use, the threads of transition portion 1265 of screw 1260 engage thethreads of washer 1270 to rigidly lock the screw to the washer. Theconvex surface of the transition portion 1265 and the concave surface ofthe washer form a ball-and-socket joint to allow for polyaxial lockingof the screw. Lip 1244 on plate hole 1240 restricts movement of thewasher beyond the lip.

FIG. 52 shows bone plating system 1320 of the present disclosure whichis identical in most respects to bone plating system 1120, describedabove. Each hole 1340 of plate 1330 includes washer 1370 that has arounded inner surface to engage screw 1360.

In yet another embodiment, FIGS. 53-54 show bone plating system 1420 ofthe present disclosure. System 1420 includes plate 1430 having holes1440 extending through the plate for receiving screws 1460 in polyaxialorientations.

Screws 1460 include at least one sharp cutting edges 1464 on head 1462to shear into plate 1430. In the illustrated embodiment, shown in FIGS.54A and 54B, the cutting edges 1464 extend around the circumference ofthe screw head. The screw is designed to fix in variable angles withrespect to a central axis of the hole due to the deformation of theplate from the cutting edges 1464 of the screw head. The screw is formedof a material harder than the plate to enable the tapping of the plateand securing of the screw.

In yet another embodiment of the present disclosure, FIGS. 55-56 showbone plating system 1520 including plate 1530 having holes 1540 foraccommodating screw 1560 in variable angles. As shown in FIG. 56, eachhole 1540 includes two lips 1544 extending around the circumference ofthe hole and acting as threads to mate with screw 1560. Each lip 1544 isinterrupted in its path around the hole by a plurality of roundedrecesses 1546 extending into the inner surface of the hole. As shown inFIG. 55, the lips have a “V-shape” cross-section. Screw 1560 is threadedand includes opposing convex and concave surfaces. The V-shape of thelips accommodates both the concave and convex surfaces of the screw. Astorque is applied to screw 1560, the threads of the screw lock to lips1544 to secure the screw to the plate.

FIGS. 57-59 show bone plating system 1620 which includes plate 1630 withholes 1640 for receiving locking screws 1660 at polyaxial orientations.As shown in FIG. 57, each hole 1640 includes countersink 1642 andengagement region 1646 extending from the countersink to bone-contactingsurface 1632.

As shown in FIG. 58, from the top view, hole 1640 has a flower-shapeconfiguration formed from a plurality of spaced apart scalloped regions1644 and screw-engaging members 1648 which are spaced apart about thecentral axis of hole 1640. Each screw-engaging member 1648 extends in adirection from countersink 1642 toward bone-contacting surface 1632 andseparates adjacent scalloped regions 1644. In the illustratedembodiment, hole 1640 includes eight equally spaced apart screw-engagingmembers 1648 and scalloped regions 1644. In this embodiment, eachscrew-engaging member 1648 defines a surface defining a width as itextends in a direction parallel to the central axis of the hole. Asshown in FIG. 57, engagement region 1646 has a converging-divergingprofile, in which an upper portion 1647 tapers toward the central axisof hole 1640 and a lower portion 1649 tapers away from the central axisof the hole 1640. Although shown with a specific number of scallopedregions and engaging members, it is to be understood that differentembodiments according to the present invention may exhibit any number ofeach element.

FIG. 59 shows locking screw 1660 positioned within hole 1640. Lockingscrew 1660 includes a conically shaped head 1662 having threads 1664 anda threaded shaft 1668. When locking screw 1660 is positioned within hole1640, threads 1664 engage screw-engaging members 1648 of hole 1640 byplastically deforming the screw-engaging members 1648 to secure thelocking screw 1660 to the bone plate 1630 at variable angles. Otherscrew designs can also be utilized, for instance, screws with curved orrounded heads.

Holes 1640 are configured to receive non-locking screws 1670 in additionto locking screws 1660. As shown in FIG. 60 non-locking screw 1670 has asubstantially rounded head 1672 and a threaded shaft 1678. This type ofscrew may or may not interact with any of the elements of the screw holein which they are placed.

FIG. 61 shows hole 1740 which is identical to hole 1640 except that eachscrew-engaging members 1748 defines a line rather than a surface as inhole 1640.

FIGS. 62 and 63 show hole 1840 which is an alternative embodiment ofholes 1640 and 1740. Each screw-engaging member 1848 includes a linethat transitions into a diamond-shaped surface 1849. Locking screw 1660engages and plastically deforms the diamond-shaped surface 1849 tosecure the screw to the hole. Further, hole 1840 differs from hole 1640in that it includes ten equally spaced apart screw-engaging members1848, as shown in FIG. 63.

FIGS. 64 and 65 show hole 1940 which is similar to hole 1640 except thatscrew-engaging members 1948 of hole 1940 form a wider surface with asubstantially constant width along the length of the surface of eachmember 1948.

During insertion of a locking screw in any of holes 1640, 1740, 1840,and 1940, a locking screw, such as locking screw 1660, is torqued withinthe hole. As the screw head rotates, the threads 1664 of screw head 1662engage at least some of the screw-engaging members 1648 to form aninterference connection between the screw-engaging members and the screwhead which causes the screw-engaging members to plastically deform. Thisconnection results in the locking of the screw to the plate and preventssubsequent loosening of the screw.

The plates described above are formed from a single piece of rigidmaterial, such as stainless steel, titanium and its alloys. In otherexamples, the plates may be formed from other biocompatible materialsincluding bioceramics and polymers. In some instances, the lockingscrews may be formed of cobalt chromium and may be harder than thematerial of the plate. In other instances the screws may be formed ofstainless steel, titanium and its alloys, etc. It is contemplated toform the plates utilizing any known manufacturing method, includingmolding, milling and additive manufacturing.

It will be appreciated that the features described in connection withindividual embodiments may be shared with others of the describedembodiments. Further, individual plates may include one or more thedescribed hole designs.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1. A bone plate comprising: a bone-contacting surface; an upper surface,opposite the bone-contacting surface; and a hole having a circumferenceand extending from the upper surface to the bone-contacting surface andincluding a first portion having a plurality of substantially parallellips, each lip extending around the circumference of the hole anddefining a diameter of the hole, the diameters of the hole as defined bythe lips decreasing in a direction from the upper surface to a center ofthe hole and increasing in a direction from the center of the holetoward the bone-contacting surface.